U.S. patent number 6,812,410 [Application Number 09/810,151] was granted by the patent office on 2004-11-02 for semiconductor module and method of manufacturing the same.
This patent grant is currently assigned to Sanyo Electric Co., Ltd.. Invention is credited to Yusuke Igarashi, Yoshiyuki Kobayashi, Eiju Maehara, Yukio Okada, Junji Sakamoto, Noriaki Sakamoto, Kouji Takahashi.
United States Patent |
6,812,410 |
Sakamoto , et al. |
November 2, 2004 |
Semiconductor module and method of manufacturing the same
Abstract
A first metal film 14 made of a Cu plated film is formed on a
radiation substrate 13A made of Al, and an island 15 exposed from a
back surface of a semiconductor device 10 is adhered thereto. At
that time, the back surface of the semiconductor device 10 is
brought into contact with contact areas, and a first opening
portion OP is opened larger than an arranging area of the
semiconductor device 10. Accordingly, the cleaning can be executed
via the first opening portion OP exposed from peripheries of the
semiconductor device 10. In addition, the heat generated from
semiconductor elements 16 can be radiated excellently from the
island 15 via a second supporting member 13A.
Inventors: |
Sakamoto; Noriaki (Gunma,
JP), Kobayashi; Yoshiyuki (Gunma, JP),
Sakamoto; Junji (Gunma, JP), Okada; Yukio (Gunma,
JP), Igarashi; Yusuke (Gunma, JP), Maehara;
Eiju (Gunma, JP), Takahashi; Kouji (Gunma,
JP) |
Assignee: |
Sanyo Electric Co., Ltd.
(Osaka, JP)
|
Family
ID: |
18803964 |
Appl.
No.: |
09/810,151 |
Filed: |
March 16, 2001 |
Foreign Application Priority Data
|
|
|
|
|
Oct 26, 2000 [JP] |
|
|
P. 2000-326841 |
|
Current U.S.
Class: |
174/260; 174/261;
257/678; 361/760; 361/783; 257/E23.092; 257/E23.101 |
Current CPC
Class: |
H01L
21/4832 (20130101); H01L 23/36 (20130101); H01L
23/4334 (20130101); H05K 3/303 (20130101); H05K
1/021 (20130101); H01L 24/32 (20130101); H05K
1/0204 (20130101); H01L 24/97 (20130101); H01L
24/49 (20130101); H01L 2924/01078 (20130101); H01L
2924/01029 (20130101); H01L 2924/351 (20130101); Y02P
70/50 (20151101); H01L 2924/18165 (20130101); H01L
2924/15311 (20130101); H01L 2924/1433 (20130101); H01L
2224/05573 (20130101); H01L 2224/32245 (20130101); H01L
2924/0103 (20130101); H01L 2924/01082 (20130101); H01L
2224/16245 (20130101); H01L 2924/01059 (20130101); H01L
2224/83385 (20130101); H05K 3/281 (20130101); H01L
2924/01006 (20130101); H05K 2201/10734 (20130101); H01L
2224/451 (20130101); H01L 2924/01005 (20130101); Y02P
70/613 (20151101); H01L 2924/0132 (20130101); H01L
2924/01046 (20130101); H01L 2924/07802 (20130101); H01L
2224/49171 (20130101); H01L 2924/15787 (20130101); H01L
2224/05571 (20130101); H01L 2224/48465 (20130101); H01L
2924/12042 (20130101); H05K 3/26 (20130101); H01L
2924/01033 (20130101); H01L 2924/3011 (20130101); H01L
24/45 (20130101); H01L 2224/48091 (20130101); H05K
2201/10416 (20130101); H01L 2924/01013 (20130101); H01L
2924/12044 (20130101); H05K 1/182 (20130101); H01L
2224/48247 (20130101); H01L 2224/73265 (20130101); H01L
2224/06135 (20130101); H01L 2224/32057 (20130101); H01L
2224/97 (20130101); H01L 24/48 (20130101); H01L
2924/01079 (20130101); H01L 24/73 (20130101); H01L
2224/92247 (20130101); H05K 2201/2036 (20130101); H01L
2924/00014 (20130101); H05K 2201/10727 (20130101); H01L
2924/181 (20130101); H01L 2924/1815 (20130101); H01L
2224/73257 (20130101); H01L 2924/01047 (20130101); H05K
1/189 (20130101); H01L 2224/48091 (20130101); H01L
2924/00014 (20130101); H01L 2224/48465 (20130101); H01L
2224/48247 (20130101); H01L 2924/00 (20130101); H01L
2224/49171 (20130101); H01L 2224/48465 (20130101); H01L
2924/00 (20130101); H01L 2224/49171 (20130101); H01L
2224/48247 (20130101); H01L 2924/00 (20130101); H01L
2924/00012 (20130101); H01L 2224/73265 (20130101); H01L
2224/32245 (20130101); H01L 2224/48247 (20130101); H01L
2924/00012 (20130101); H01L 2924/0132 (20130101); H01L
2924/01026 (20130101); H01L 2924/01028 (20130101); H01L
2924/0132 (20130101); H01L 2924/01046 (20130101); H01L
2924/01047 (20130101); H01L 2224/92247 (20130101); H01L
2224/73265 (20130101); H01L 2224/32245 (20130101); H01L
2224/48247 (20130101); H01L 2924/00 (20130101); H01L
2224/48465 (20130101); H01L 2224/48091 (20130101); H01L
2924/00 (20130101); H01L 2924/07802 (20130101); H01L
2924/00 (20130101); H01L 2224/97 (20130101); H01L
2224/83 (20130101); H01L 2224/97 (20130101); H01L
2224/85 (20130101); H01L 2224/451 (20130101); H01L
2924/00 (20130101); H01L 2924/351 (20130101); H01L
2924/00 (20130101); H01L 2924/15787 (20130101); H01L
2924/00 (20130101); H01L 2224/451 (20130101); H01L
2924/00014 (20130101); H01L 2924/12042 (20130101); H01L
2924/00 (20130101); H01L 2224/97 (20130101); H01L
2224/73265 (20130101); H01L 2224/32245 (20130101); H01L
2224/48247 (20130101); H01L 2924/00 (20130101); H01L
2924/00014 (20130101); H01L 2224/05599 (20130101); H01L
2924/181 (20130101); H01L 2924/00012 (20130101) |
Current International
Class: |
H01L
21/48 (20060101); H01L 21/02 (20060101); H05K
1/02 (20060101); H05K 3/30 (20060101); H01L
23/36 (20060101); H01L 23/433 (20060101); H01L
23/34 (20060101); H05K 3/28 (20060101); H05K
1/18 (20060101); H05K 3/26 (20060101); H05K
001/16 () |
Field of
Search: |
;174/260,261
;361/760,764,767,777,783 ;257/778,784,787,678 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Nikkei Electronics, vol. 6.16 (No. 691) pp. 92-120 (1997)..
|
Primary Examiner: Cuneo; Kamand
Assistant Examiner: Patel; I B
Attorney, Agent or Firm: Fish & Richardson PC
Claims
What is claimed is:
1. A semiconductor module comprising: a semiconductor device in
which semiconductor elements are sealed integrally by an insulating
resin and back surface electrodes that are electrically connected
to the semiconductor elements are exposed from a back surface; and
a flexible sheet having at least a plurality of conductive
patterns, a first insulating sheet for supporting pad electrodes
formed at end potions of said conductive patterns and electrically
connected to said back surface electrodes, and a second insulating
sheet for covering the conductive patterns; wherein an opening
portion from which the pad electrodes are exposed and whose size is
larger than a back surface of the semiconductor device is formed in
the second insulating sheet, and contact areas which come into
contact with at least three areas of a back surface of the
insulating resin are provided to the opening portion.
2. A semiconductor module according to claim 1, wherein the contact
areas are formed of the second insulating sheet.
3. A semiconductor module according to claim 2, wherein the contact
areas are formed integrally with the second insulating sheet.
4. A semiconductor module according to claim 1, wherein the contact
areas are formed of material which is different from the second
insulating sheet.
5. A semiconductor module comprising: a semiconductor device in
which semiconductor elements are sealed integrally by an insulating
resin, back surface electrodes that are electrically connected to
the semiconductor elements are exposed from a back surface at a
same surface level as a back surface of the insulating resin or a
hollow surface level rather than the back surface, and an island
provided to a lower surface of the semiconductor element is exposed
at the same surface level as the back surface of the insulating
resin or the hollow surface level rather than the back surface; and
a flexible sheet having at least a plurality of conductive
patterns, a first insulating sheet for supporting pad electrodes
formed at end potions of said conductive patterns and electrically
connected to said back surface electrodes, and a second insulating
sheet for covering the conductive patterns; wherein a first opening
portion from which the pad electrodes are exposed and whose size is
larger than a back surface of the semiconductor device is formed in
the second insulating sheet, and a second opening portion which
exposes the island from a back surface of the first insulating
sheet is formed in the first insulating sheet, and contact areas
which come into contact with at least three areas of the back
surface of the insulating resin are provided between the first
opening portion and the second opening portion.
6. A semiconductor module according to claim 5, wherein the contact
areas are formed of the second insulating sheet.
7. A semiconductor module according to claim 6, wherein the contact
areas are formed integrally with the second insulating sheet.
8. A semiconductor module according to claim 5, wherein the contact
areas are formed of material which is different from the second
insulating sheet.
9. A semiconductor module according to any one of claim 5 to claim
8, wherein a radiation substrate is stuck onto a back surface of
the first insulating sheet to close the second opening portion, and
the radiation substrate and the island are thermally coupled with
each other.
10. A semiconductor module according to claim 9, wherein a first
metal film which contains Cu, Ag or Au as major material and is
formed by plating is formed as an uppermost layer on a first
surface of the radiation substrate, and the first metal film and
the island are adhered to (or are brought into contact with) each
other by brazing solder, conductive paste, or adhesive material
which is excellent in thermal conductivity.
11. A semiconductor module according to claim 9, wherein the first
surface of the radiation substrate and the island are adhered to
(or are brought into contact with) each other by brazing solder,
conductive paste, or adhesive material which is excellent in
thermal conductivity.
12. A semiconductor module according to any one of claim 5 to claim
8, wherein a radiation substrate is stuck onto a back surface of
the first insulating sheet to close the second opening portion, and
a metal plate containing Cu as a major component is adhered between
the radiation substrate and the island.
13. A semiconductor module according to claim 12, wherein the
island and the metal plate are substantially formed of same
material.
14. A semiconductor module according to claim 12, wherein the
radiation substrate and the metal plate are formed integrally of
same material.
15. A semiconductor module comprising: a semiconductor device in
which semiconductor elements are sealed integrally in a face-up or
face-down fashion by an insulating resin, back surface electrodes
that are electrically connected to bonding electrodes of the
semiconductor elements are exposed from a back surface at a same
surface level as a back surface of the insulating resin or a hollow
surface level rather than the back surface, and an island provided
to a lower surface of the semiconductor element is exposed at the
same surface level as the back surface of the insulating resin or
the hollow surface level rather than the back surface; and a
flexible sheet having at least a plurality of conductive patterns,
a first insulating sheet for supporting pad electrodes formed at
end potions of said conductive patterns and electrically connected
to said back surface electrodes, and a second insulating sheet for
covering the conductive patterns; wherein a first opening portion
from which the pad electrodes are exposed and whose size is larger
than a back surface of the semiconductor device is formed in the
second insulating sheet, and a second opening portion from which a
radiation substrate being stuck onto an area corresponding to the
island is exposed is provided to a back surface of the first
insulating sheet, and contact areas which come into contact with at
least three areas of the back surface of the insulating resin are
provided between the first opening portion and the second opening
portion, and the contact areas come into contact with the back
surface of the insulating resin, and the island and the radiation
substrate are thermally coupled with each other.
16. A semiconductor module according to claim 15, wherein side
surfaces of the back surface electrodes and the back surface of the
insulating resin extended from the side surfaces of the back
surface electrodes have a same curved surface.
17. A semiconductor module according to claim 15 or claim 16,
wherein the semiconductor element is a read/write amplifier IC of a
hard disk.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device and a
semiconductor module and, more particularly, a structure that is
able to radiate excellently the heat from the semiconductor
element.
In recent years, application of the semiconductor device to the
mobile device and the small and high density packaging device makes
progress, and thus not only the reduction in size and weight but
also the good radiating characteristic is requested. Also, the
semiconductor device is mounted onto various substrates, and the
semiconductor module containing the substrate is mounted in various
devices. As the substrate, there are the ceramic substrate, the
printed circuit board, the flexible sheet, the metal substrate, the
glass substrate, etc. Here, as the semiconductor module mounted
onto the flexible sheet, an example will be explained hereunder. In
this case, it is needless to say that these substrates can be
employed in embodiments.
A hard disk 100 into which the semiconductor module employing the
flexible sheet is mounted is shown in FIG. 25. For example, this
hard disk 100 is described in detail in Nikkei Electronics, 1997,
Jun. 16 (No.691), p92-.
This hard disk 100 is packaged into a casing 101 formed of metal,
and plural sheet of recording disks 102 are fitted integrally to a
spindle motor 103. A magnetic head 104 is arranged over a surface
of the recording disk 102 via a minute clearance respectively. This
magnetic head 104 is fitted to a top end of a suspension 106 that
is fixed to the top of an arm 105. Then, an integral structure
consisting of the magnetic heads 104, the suspension 106, and the
arm 105 is fitted to an actuator 107.
The recording disks 102 must be connected electrically to a
read/write amplifier IC 108 to execute the writing/reading via the
magnetic heads 104. Thus, a semiconductor module 110 in which the
read/write amplifier IC 108 is mounted onto a flexible sheet 109 is
employed. Wirings provided on the flexible sheet 109 are finally
connected electrically the magnetic heads 104. The semiconductor
module 110 is called the flexible circuit assembly and is normally
abbreviated to FCA.
A connector 111 fitted onto the semiconductor module 110 is exposed
from a back surface of the casing 101. This connector (male or
female type) 111 is connected to another connector (female or male
type) fitted to a main board 112. Also, wirings are provided on the
main board 112, and also a driving IC for the spindle motor 103, a
buffer memory, other driving ICs, e.g., ASIC, etc. are mounted.
For example, the recording disk 102 is rotated by the spindle motor
103 at 4500 rpm, and a position of the magnetic head 104 is decided
by the actuator 107. Since this rotating mechanism is tightly
sealed by a lid provided to the casing 101, the heat is filled
inevitably in the casing 101 and thus the temperature of the
read/write amplifier IC 108 is increased. Therefore, the read/write
amplifier IC 108 is positioned on the actuator 107, the casing 101,
or the like, that has excellent thermal conduction. Also, the
rotation of the spindle motor 103 tends to increase such as 5400,
7200, 10000 rpm, and thus this heat radiation becomes important
more and more.
In order to explain the above semiconductor module (FCA) 110
further more, a structure of the semiconductor module is shown in
FIG. 26. FIG. 26A is a plan view and FIG. 26B is a sectional view
in which the read/write amplifier IC 108 provided to the top
portion is cut out along an A-A line. Since this FCA 110 is folded
and then fitted into a part of the casing 101, a first flexible
sheet 109 having a flat shape that can be easily folded is
employed.
The connector 111 is fitted to the left end of the FCA 110 to act
as a first connector portion. First wirings 121 electrically
connected to the connector 111 are stuck to the first flexible
sheet 109 and then extended to the right end. Then, the first
wirings 121 are electrically connected to the read/write amplifier
IC 108. Also, leads 122 of the read/write amplifier IC 108
connected to the magnetic heads 104 are connected to second wirings
123. The second wirings 123 are electrically connected to third
wirings 126 on the second flexible sheet 124 provided over the arm
105 and the suspension 106. That is, the right end of the first
flexible sheet 109 constitutes a second connecting portion 127, and
is connected to the second flexible sheet 124 there. The first
flexible sheet 109 and the second flexible sheet 124 may be
integrally formed. In this case, the second wirings 123 and the
third wirings 126 are integrally provided.
A supporting member 128 is provided on a back surface of the first
flexible sheet 109 on which the read/write amplifier IC 108 is
provided. The ceramic substrate or the Al substrate is employed as
this supporting member 128. The heat generated by the read/write
amplifier IC 108 can be discharged since the metals exposed in the
casing 101 is thermally coupled with the outside via the supporting
member 128.
Then, a connection structure of the read/write amplifier IC 108 and
the first flexible sheet 109 will be explained with reference to
FIG. 26B hereunder.
This first flexible sheet 109 is formed by laminating a first
polyimide sheet 130 (referred to as a "first PI sheet"
hereinafter), a first adhering layer 131, a conductive pattern 132,
a second adhering layer 133, and a second polyimide sheet 134
(referred to as a "second PI sheet" hereinafter) from the bottom.
The conductive pattern 132 is sandwiched between the first PI sheet
130 and the second PI sheet 134.
Also, in order to connect the read/write amplifier IC 108, an
opening portion 135 is formed by removing the second PI sheet 134
and the second adhering layer 133 from a desired area to expose the
conductive pattern 132. Then, as shown in FIG. 26B, the read/write
amplifier IC 108 is electrically connected via the leads 122.
In FIG. 26B, the heat is radiated from the semiconductor device
being packaged with an insulating resin 136 to the outside via the
heat radiation path indicated by arrows. More particularly, the
semiconductor device in the prior art has such a structure that,
since an insulating resin 136 acts as a thermal resistance, the
heat generated from the read/write amplifier IC 108 cannot be
effectively discharged to the outside in total.
Then, the hard disk will be explained hereunder. The transfer rate
of the hard disk in reading/writing needs the frequency of 500 MHz
to 1 GHz, or more so as to increase the reading/writing speed of
the read/write amplifier IC 108. Therefore, the wiring path on the
flexible sheet connected to the read/write amplifier IC 108 must be
reduced and also the increase in the temperature of the read/write
amplifier IC 108 must be prevented.
In particular, since the recording disks 102 are rotated at a high
speed and are installed in a space of the casing 101 tightly sealed
by the lid, the temperature in the casing 101 is increased up to
about 70 to 80.degree. C. In contrast, the allowable operating
temperature of the normal IC is about 125.degree. C., and the
temperature increase of about 45.degree. C. from the internal
temperature of 80.degree. C. can be accepted for the read/write
amplifier IC 108. However, as shown in FIG. 26B, if the thermal
resistance of the semiconductor device per se or the thermal
resistance of the FCA is large, the read/write amplifier IC 108
exceeds immediately the allowable operating temperature and cannot
exhibit its essential ability. As a result, the semiconductor
device or FCA having the excellent radiation characteristic is
requested.
In addition, there is such a problem that, since the operating
frequency is further increased in the future, the temperature
increase of the read/write amplifier IC 108 itself is brought about
by the heat generated by the operating process. Although the target
operating frequency can be achieved in the normal temperature, the
operating frequency must be lowered because of its temperature
increase in the inside of the hard disk.
As described above, with the increase of the operating frequency in
the future, the better radiation characteristic is required for the
semiconductor device or the semiconductor module (FCA).
In contrast, the actuator 107 itself, or the arm 105 fitted to the
actuator 107, the suspension 106, and the magnetic head 104 must be
reduced in weight to reduce their moment of inertia. Especially, as
shown in FIG. 25, in case the read/write amplifier IC 108 is
mounted on the surface of the actuator 107 or the arm 105, the
reduction in weight of the IC 108 and the FCA 110 is also
requested.
Moreover, as shown in FIG. 27, there is a semiconductor device in
which the island 137 of the read/write amplifier IC 108 is exposed
from the insulating resin 136 and the back surface of the island
137 and the contact surface of the lead 122 are formed at the same
surface level. In this case, there is the problem, since the
connecting means such as the solder, etc., that is formed between
the lead 122 and the conductive pattern 132, is formed very thin
and thus the clearance between the island 137 and the second PI
sheet 134 is very narrow, it is difficult to clean this
clearance.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above subjects,
and can overcome these subjects by satisfying following respects.
First, there is provided a semiconductor module comprising: a
semiconductor device in which semiconductor elements are sealed
integrally by an insulating resin and back surface electrodes that
are electrically connected to the semiconductor elements are
exposed from a back surface; and a flexible sheet having at least a
plurality of conductive patterns, a first insulating sheet for
supporting pad electrodes formed at end potions of said conductive
patterns and electrically connected to said back surface
electrodes, and a second insulating sheet for covering the
conductive patterns; wherein an opening portion from which the pad
electrodes are exposed and whose size is larger than a back surface
of the semiconductor device is formed in the second insulating
sheet, and contact areas which come into contact with at least
three areas of a back surface of the insulating resin are provided
to the opening portion.
If the thickness of contact areas is set to about 40 to 50 .mu.m or
more, the clearance can be formed between the back surface of the
semiconductor device and the first insulating sheet and can be
cleaned.
Second, the contact areas are formed of the second insulating
sheet. As shown in FIG. 1 and FIG. 4, the second insulating sheet
is employed as the spacers, the clearance can be formed on the back
surface of the semiconductor device.
Third, the contact areas are formed integrally with the second
insulating sheet.
Fourth, the contact areas are formed of material which is different
from the second insulating sheet.
Fifth, there is provided a semiconductor module comprising: a
semiconductor device in which semiconductor elements are sealed
integrally by an insulating resin, back surface electrodes that are
electrically connected to the semiconductor elements are exposed
from a back surface at a same surface level as a back surface of
the insulating resin or a hollow surface level rather than the back
surface, and an island provided to a lower surface of the
semiconductor element is exposed at the same surface level as the
back surface of the insulating resin or the hollow surface level
rather than the back surface; and a flexible sheet having at least
a plurality of conductive patterns, a first insulating sheet for
supporting pad electrodes formed at end potions of said conductive
patterns and electrically connected to said back surface
electrodes, and a second insulating sheet for covering the
conductive patterns; wherein a first opening portion from which the
pad electrodes are exposed and whose size is larger than a back
surface of the semiconductor device is formed in the second
insulating sheet, and a second opening portion which exposes the
island from a back surface of the first insulating sheet is formed
in the first insulating sheet, and contact areas which come into
contact with at least three areas of the back surface of the
insulating resin are provided between the first opening portion and
the second opening portion.
Since the island of the semiconductor device is exposed from the
back surface of the flexible sheet, it can be directly adhered to
the material having good thermal conductivity. In addition, the
clearance can be formed on the back surface of the semiconductor
device because the contact areas act as the spacers, this clearance
can be cleaned.
Sixth, the contact areas are formed of the second insulating
sheet.
Seventh, the contact areas are formed integrally with the second
insulating sheet.
Eighth, the contact areas are formed of material which is different
from the second insulating sheet.
Ninth, a radiation substrate is stuck onto a back surface of the
first insulating sheet to close the second opening portion, and the
radiation substrate and the island are thermally coupled with each
other.
Since the island and the semiconductor device are thermally coupled
with each other by the solder, etc., the heat generated from the
semiconductor device can be transferred to the radiation
substrate.
Tenth, a first metal film which contains Cu, Ag or Au as major
material and is formed by plating is formed as an uppermost layer
on a first surface of the radiation substrate, and the first metal
film and the island are adhered to (or are brought into contact
with) each other by brazing solder, conductive paste, or adhesive
material which is excellent in thermal conductivity.
If Al is employed as the radiation substrate, the radiation
substrate and the island can be adhered to each other via the
brazing solder by forming the Cu, Ag or Au plated film on the
outermost surface.
Eleventh, the first surface of the radiation substrate and the
island are adhered to (or are brought into contact with) each other
by brazing solder, conductive paste, or adhesive material which is
excellent in thermal conductivity.
Twelfth, a radiation substrate is stuck onto a back surface of the
first insulating sheet to close the second opening portion, and a
metal plate containing Cu as a major component is adhered between
the radiation substrate and the island.
When the back surface electrodes and the pad electrodes are
connected to each other, the clearance is formed between the island
and the radiation substrate by the thickness of the conductive
pattern and the thickness of the first insulating sheet. In this
case, the metal plate having the thickness almost equal to this
clearance can be inserted, the island and the radiation substrate
can be excellently thermally coupled with each other.
Thirteenth, the island and the metal plate are substantially formed
of same material.
If the projection is formed on the island, the island can be
thermally coupled with the radiation substrate without employment
of another metal plate.
Fourteenth, the radiation substrate and the metal plate are formed
integrally of same material.
If the projection is formed by applying the press, etc. to the
radiation substrate, the island can be thermally coupled with the
radiation substrate without employment of another metal plate.
Fifteenth, there is provided a semiconductor module comprising: a
semiconductor device in which semiconductor elements are sealed
integrally in a face-up or face-down fashion by an insulating
resin, back surface electrodes that are electrically connected to
bonding electrodes of the semiconductor elements are exposed from a
back surface at a same surface level as a back surface of the
insulating resin or a hollow surface level rather than the back
surface, and an island provided to a lower surface of the
semiconductor element is exposed at the same surface level as the
back surface of the insulating resin or the hollow surface level
rather than the back surface; and a flexible sheet having at least
a plurality of conductive patterns, a first insulating sheet for
supporting pad electrodes formed at end potions of said conductive
patterns and electrically connected to said back surface
electrodes, and a second insulating sheet for covering the
conductive patterns; wherein a first opening portion from which the
pad electrodes are exposed and whose size is larger than a back
surface of the semiconductor device is formed in the second
insulating sheet, and a second opening portion from which a
radiation substrate being stuck onto an area corresponding to the
island is exposed is provided to a back surface of the first
insulating sheet, and contact areas which come into contact with at
least three areas of the back surface of the insulating resin are
provided between the first opening portion and the second opening
portion, and the contact areas come into contact with the back
surface of the insulating resin, and the island and the radiation
substrate are thermally coupled with each other.
Sixteenth, side surfaces of the back surface electrodes and the
back surface of the insulating resin extended from the side
surfaces of the back surface electrodes have a same curved
surface.
Seventeenth, the semiconductor element is a read/write amplifier IC
of a hard disk.
Eighteenth, there is provided a method of manufacturing a
semiconductor module, comprising the steps of: preparing a
semiconductor device in which semiconductor elements are sealed
integrally by an insulating resin and back surface electrodes that
are electrically connected to the semiconductor elements and an
island provided below the semiconductor elements are exposed from a
back surface, and a flexible sheet having at least a plurality of
conductive patterns, a first insulating sheet for supporting pad
electrodes formed at end potions of said conductive patterns and
electrically connected to said back surface electrodes, and
island-like electrodes adhered to said island, and a second
insulating sheet for covering the conductive patterns, wherein an
opening portion from which the pad electrodes and the island-like
electrode are exposed and whose size is larger than a back surface
of the semiconductor device is formed in the second insulating
sheet; connecting electrically the pad electrodes and the back
surface electrodes and mounting the semiconductor device via
spacers provided under the semiconductor device; and cleaning a
clearance formed by the spacers via the opening portion exposed
from peripheries of the semiconductor device.
Since the cleaning liquid can be permeated into the clearance, the
degradation or the failure of the electrical connecting portions
arranged in the clearance can be prevented.
Nineteenth, there is provided a method of manufacturing a
semiconductor module, comprising the steps of: preparing a
semiconductor device in which semiconductor elements are sealed
integrally by an insulating resin and back surface electrodes that
are electrically connected to the semiconductor elements are
exposed from a back surface, and a flexible sheet having at least a
plurality of conductive patterns, a first insulating sheet for
supporting pad electrodes formed at end potions of said conductive
patterns and electrically connected to said back surface
electrodes, and a second insulating sheet for covering the
conductive patterns, wherein an opening portion from which the pad
electrodes are exposed and whose size is larger than a back surface
of the semiconductor device is formed in the second insulating
sheet; connecting electrically the pad electrodes and the back
surface electrodes and mounting the semiconductor device while
providing a clearance on a back surface via contact areas provided
integrally with the first insulating sheet; and cleaning the
clearance formed on the back surface of the semiconductor device
via the opening portion exposed from peripheries of the
semiconductor device.
Twentieth, there is provided a method of manufacturing a
semiconductor module, comprising the steps of: preparing a
semiconductor device in which semiconductor elements are sealed
integrally by an insulating resin and an island provided below the
semiconductor elements and back surface electrodes that are
electrically connected to the semiconductor elements are exposed
from a back surface, and a flexible sheet having at least a
plurality of conductive patterns, a first insulating sheet for
supporting pad electrodes formed at end potions of said conductive
patterns and electrically connected to said back surface electrodes
and from which a radiation substrate stuck onto a back surface is
exposed, and a second insulating sheet for covering the conductive
patterns, wherein an opening portion from which the pad electrodes
and the radiation substrate are exposed and whose size is larger
than a back surface of the semiconductor device is formed in the
second insulating sheet; connecting electrically the pad electrodes
and the back surface electrodes, coupling thermally the island with
the radiation substrate, and mounting the semiconductor device
while providing a clearance on a back surface via contact areas
provided at at least three areas of the back surface of the
insulating resin; and cleaning the back surface of the
semiconductor device via the opening portion exposed from
peripheries of the semiconductor device.
Twenty-first, underfill is mixed into the back surface of the
semiconductor device after the cleaning.
BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 is a view showing a semiconductor module of the present
invention;
FIGS. 2A to 2C are enlarged views showing an pertinent portion in
FIG. 1;
FIG. 3 is a view showing a variation of FIG. 2;
FIGS. 4A to 4D are views showing another variation of FIG. 2;
FIGS. 5A to 5C are views showing a radiation substrate and a metal
film formed on the radiation substrate;
FIGS. 6A and 6B are views showing a semiconductor device of the
present invention;
FIGS. 7A and 7B are views showing a semiconductor device of the
present invention;
FIGS. 8A to 8C are views showing a semiconductor device of the
present invention;
FIG. 9 is a view showing a semiconductor module of the present
invention;
FIGS. 10A and 10B are views showing a semiconductor device of the
present invention;
FIGS. 11A and 11B are views showing a semiconductor device of the
present invention;
FIGS. 12A to 12C are views showing a semiconductor device of the
present invention;
FIG. 13 is a view showing a semiconductor module of the present
invention;
FIG. 14 is a view showing a semiconductor device of the present
invention;
FIG. 15 is a view showing a semiconductor device of the present
invention;
FIG. 16 is a view showing a method of manufacturing a semiconductor
device of the present invention;
FIG. 17 is a view showing a method of manufacturing a semiconductor
device of the present invention;
FIG. 18 is a view showing a method of manufacturing a semiconductor
device of the present invention;
FIG. 19 is a view showing a method of manufacturing a semiconductor
device of the present invention;
FIG. 20 is a view showing a method of manufacturing a semiconductor
device of the present invention;
FIG. 21 is a view showing a method of manufacturing a semiconductor
device of the present invention;
FIG. 22 is a view showing a method of manufacturing a semiconductor
device of the present invention;
FIG. 23 is a view showing a method of manufacturing a semiconductor
device of the present invention;
FIG. 24 is a view showing a semiconductor module of the present
invention;
FIG. 25 is a view showing a hard disk;
FIGS. 26A and 26B are views showing a semiconductor module employed
in FIG. 25 in the conventional art; and
FIG. 27 is a view showing a semiconductor module in the
conventional art.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention provides a light-weight and small-size
semiconductor device having the high radiation characteristic and
also provides a semiconductor module in which the semiconductor
device is mounted, e.g., a semiconductor module in which the
semiconductor device is adhered to (or is brought into contact
with) a radiation substrate and a semiconductor module in which the
semiconductor device is mounted on the flexible sheet and the
radiation substrate is adhered to (or is brought into contact with)
a back surface of the flexible sheet (called "FCA" hereinafter),
and achieves improvement in the characteristic of a precision
equipment, e.g., a hard disk, into which the semiconductor module
is installed.
First, a hard disk 100 as an example of the equipment, into which
the semiconductor module is installed, is shown in FIG. 25 and the
semiconductor module is shown in FIGS. 1 to 4, FIG. 9, FIG. 13, and
FIG. 24. Also, the semiconductor device that is mounted in the
semiconductor module is shown in FIG. 6 to FIG. 8, FIG. 10 to FIG.
12, FIG. 14 and FIG. 15 and a method of manufacturing the same is
shown in FIG. 16 to FIG. 23.
[First Embodiment Explaining the Equipment in Which the
Semiconductor Module is Mounted]
As this equipment, the hard disk 100 explained in the prior art
column and shown in FIG. 25 will be explained once again.
The hard disk 100 is mounted on the main board 112 at need to
install into the computer, etc. A female type (or male type)
connector is fitted to this main board 112. Then, the connector is
mounted into the FCA, and thus the male type (or female type)
connector 111 exposed from a back surface of the casing 101 is
connected to a connector on the main board 112. Also, plural sheets
of recording disks 102 as recording medium are laminated in the
casing 101 according to its capacity. Since the magnetic head 104
is scanned while floating over the recording disk 102 with a gap of
almost 20 to 30 nm, an interval between the recording disks 102 is
set to an interval that causes no trouble in such scanning. Then,
the recording disks 102 are attached to the spindle motor 103 to
keep this interval. The spindle motor 103 is fitted to a mounting
substrate, and the connector arranged on a back surface of the
mounting substrate is exposed from the back surface of the casing
101. Then, this connector is connected to the connector of the main
board 112. Accordingly, an IC for driving the read/write amplifier
IC 108 of the magnetic head 104, an IC for driving the spindle
motor 103, an IC for driving the actuator 107, a buffer memory for
temporarily saving the data, ASIC used to achieve the original
drive of the maker, etc. are mounted on the main board 112. Of
course, other passive elements and active elements may be mounted
on the main board 112.
Then, wirings for connecting the magnetic heads 104 and the
read/write amplifier IC 108 are considered as short in length as
possible, and the read/write amplifier IC 108 is arranged in the
actuator 107. However, since the semiconductor device of the
present invention explained hereinafter is small in size and light
in weight, such semiconductor device may be mounted on the arm 105
or the suspension 106 except the actuator. In this case, as shown
in FIG. 1A, since the back surface of the semiconductor device 10
is exposed from the second opening portion 13 of the first
supporting member (flexible sheet) 11, such back surface of the
semiconductor device 10 is thermally coupled with the arm 105 or
the suspension 106, the heat of the semiconductor device 10 can be
emitted to the outside via the arm 105 and the casing 101.
If the semiconductor device is mounted in the actuator 107 as shown
in FIG. 25, all reading/writing circuits for respective channel of
the read/write amplifier IC 108 are formed by a one-chip device
such that a plurality of magnetic sensors can read and write. In
this case, the reading/writing circuits used exclusively for the
magnetic heads 104 fitted to respective suspensions 106 may be
mounted in respective suspensions or arms. In this manner, wiring
distances between the magnetic heads 104 and the read/write
amplifier IC 108 can be considerably shortened rather than the
structure shown in FIG. 25. Thus, the reduction in the impedance
can be achieved accordingly and thus the improvement of the
reading/writing speed can be achieved.
Since the magnetic head 104 is scanned while floating over the
recording disk 102 with a gap of almost 20 to 30 nm, it is apt to
be very easily damaged by particles. That is, since the high
precision electronic equipment has a driving portion and a sliding
portion, an Al substrate that is light in weight and hardly
generates the particles is employed as a radiation substrate
13A.
Al is light and excellent in the thermal conduction, and an oxide
film formed on a surface is thin and dense. If this dense oxide
film is formed once, the oxygen is hard to reach Al and thus the
growth of the oxide film is almost stopped. That is, in the above
precision equipment, an oxide film is easily grown on Cu, for
example, and an amount of particles generated from the oxide film
is increased to cause the malfunction as the oxide film is grown
much more in the equipment. However, the growth of the oxide film
is reduced on the substrate that employs Al or stainless steel as
major material, the generation of the particles is small
correspondingly and thus the damage or the malfunction of the
recording disk can be reduced.
In contrast, Al and the oxide formed on the surface of Al have no
affinity for conductive adhering material (brazing solder such as
solder, etc., conductive paste such as Ag, Au, etc.). However, a
first metal film 14 using Cu, Ag, or Au as major material can be
formed on the surface of Al. This is shown in FIG. 5. Therefore, if
this first metal film 14 is formed on an Al radiation substrate
13A, an island 15 exposed from the back surface of the
semiconductor device 10 can be thermally coupled with the radiation
substrate 13A via the conductive adhering material (the brazing
solder, the conductive paste, the anisotropic conductive resin,
etc.). As a result, the Al substrate can be caused to operate as
the radiation substrate 13A that hardly generates the particles and
has excellent thermal conductivity.
[Second Embodiment Explaining the Radiation Substrate 13A]
The fact is known that, since Al oxide is formed on the surface of
the radiation substrate 13A using Al as major material, the metal
cannot be adhered onto the surface via the brazing solder such as
solder, the conductive paste, or the like. Accordingly, it is known
that there is no means to adhere the Al substrate and the island 15
exposed from the back surface of the semiconductor device 10 except
that they must be adhered to each other via the adhesive or the
insulating connecting means having good thermal conduction.
However, Al can be plated with Cu, Ag, or Au by the plating method.
Thus, as shown in FIG. 5, if the plated film can be formed as the
first metal film 14, the metal body 15 such as the island, the
metal plate, etc. can be adhered onto the plated film via the
brazing solder.
In addition, since no insulating material is interposed between the
island 15 and the radiation substrate 13A, the thermal resistance
is very small. Thus, the heat generated from the semiconductor
element 16 can be emitted from a metal member constituting an
electronic equipment to the outside.
Then, a method of forming the metal film made of Cu on the Al
substrate will be explained hereunder.
First, the Al substrate is lightly etched with ammonium persulfate
and then immersed in an acid such as sulfuric acid, etc. A
concentration of the sulfuric acid is 100 ml/l, and the Al
substrate is immersed at the atmospheric temperature for about one
minute. In this case, l indicates liter.
Second, the oxide film and the contamination on the Al substrate is
removed and then Pd 14A acting as the catalyst is arranged.
Especially, since Pd 14A is separated out concentratively into one
area, the process for scattering Pd 14A to arrange is executed.
Third, a Cu film 14B of about 0.2 .mu.m thickness is generated by
the electroless Cu plating method by using Pd 14A as the catalyst.
Here Pd 14A acts as the nucleus and the Cu film 14B is generated on
the Al substrate 13A. Then, the Cu film 14B is cleaned by the
sulfuric acid and then is plated with the copper sulfate by the
electrolytic plating at the atmospheric temperature for 60 minutes.
Accordingly, the Cu film 14 of about 20 .mu.m thickness is
grown.
According to above steps, the Cu plated film 14 is formed on the
outermost surface of the Al substrate to have a film thickness of
about 20 .mu.m. Since the Cu plated film 14 can be adhered to the
island 15 containing Cu as main material via the brazing solder,
the Al substrate can be provided as the radiation substrate 13A
that has excellent thermal conduction and seldom generates the
particles.
Therefore, the semiconductor device can be adhered to a first
surface 18, and then a second surface 19 can be brought into
contact with the constituent element 17 constituting the electronic
equipment, e.g., the inside of the casing, the actuator, and the
arm, as shown in FIG. 9.
Also, the first metal film 14 is formed in one area of the Al
substrate 13A, and then the oxide film 20 is grown once again in
areas other than this one area.
Also, following methods may be employed.
First, Ni or Cu can be plated by the step called the zincate
process. At first, after the Al substrate 13A is subjected to the
alkaline degreasing and the alkaline etching, the zincate process
is applied. This is applied to form the Zn film of about 0.1 to 0.2
.mu.m and then form Cu or Ni by the electroless or electrolytic
plating.
Second, the Al substrate 13A is subjected to the alkaline
degreasing and the alkaline etching, then Ni is formed the
electroless plating, and then Au is plated. In this manner, if Cu
or Au is not directly plated on the Al substrate but Cu or Au is
formed after a very thin film (Zn, Pd, etc.) is formed on the Al
substrate, a film to which soldering is applicable can be formed on
the radiation substrate. In addition, since all films are excellent
in thermal conduction, such radiation substrate has the very
excellent radiation characteristic. In this case, three type Cu
film forming methods are shown herein, but any film forming method
may be employed if material to the outermost surface of which the
brazing solder, the conductive paste, etc. can be adhered may be
coated. FIG. 5B shows the radiation substrate 13A in which the
metal plate is adhered onto the first metal film, and FIG. 5C shows
the radiation substrate 13A in which the convex shape is formed by
the press. If this structure is employed, there is no need to form
the back surface of the semiconductor device as the projected
shape, as shown in FIG. 7.
[Third Embodiment Explaining the Semiconductor Device]
In the semiconductor module shown in FIG. 1, the face-up
semiconductor device 10 is mounted onto the flexible sheet 11, and
concrete structures of the semiconductor device 10 are shown in
FIG. 6 to FIG. 8.
In the semiconductor device 10A shown in FIG. 6, bonding pads
(corresponding to the back surface electrode) 21 and the island 15
are arranged substantially on the same surface and the brazing
solder 22 shown herein is directly adhered to the radiation
substrate 13A or the first metal film 14 formed on the radiation
substrate 13A. In the semiconductor device 10B shown in FIG. 7A,
the metal plate 23 is adhered to the island 15 via the brazing
solder 22 and projected from the back surfaces of the bonding pads
21. In the semiconductor device 10C shown in FIG. 7B, the island 15
is formed integrally with the metal plate 23 and the back surface
is also projected rather than the bonding pads 21. In the
semiconductor device 10D shown in FIG. 8A, the island 15 is omitted
and the back surface of the semiconductor element 16 substantially
coincides in level with the back surfaces of the bonding pads 21.
Also, in the semiconductor device 10E shown in FIG. 8B, the metal
plate 23 is directly adhered to the back surface of the
semiconductor element 16 via the brazing solder 22 to project the
back surface of the metal plate 23. Finally, in the semiconductor
device 10F shown in FIG. 8C, the metal plate 23 is directly adhered
to the conductive film 24 formed on the back surface of the
semiconductor element 16 to project from the back surfaces of the
bonding pads 21.
Then, the semiconductor device 10A of the present invention will be
explained with reference to FIG. 6 hereunder. FIG. 6A is a plan
view of the semiconductor device and FIG. 6B is a sectional view
taken along an A-A line.
In FIG. 6, following constituent elements are buried into an
insulating resin 25. That is, the bonding pads 21 . . . , the
island 15 provided in the region surrounded by the bonding pads 21,
and the semiconductor element 16 provided on the island 15 are
buried. In this case, since the semiconductor element 16 is mounted
in a face-up fashion, the bonding electrodes 27 of the
semiconductor element 16 are electrically connected to the bonding
pads 21 via the bonding wires 26.
Also, when the island 15 and the semiconductor element 16 are
electrically connected to each other, they are adhered by the
conductive material. Also, when there is no necessity that the
island 15 and the semiconductor element 16 are electrically
connected to each other, they are adhered via an insulating
adhering means. Since this insulating adhering means causes the
thermal resistance, the insulating adhering means in which fillers
are mixed to have the small thermal resistance is preferable. Here,
Au is coated on the back surface of the semiconductor element, then
Ag is formed on the surface of the island, and then both are
adhered to each other by the solder 28 (or the Ag paste).
Also, the back surfaces of the bonding pads 21 are exposed from the
insulating resin 25, and act as the external connection electrode
29A as they are. Side surfaces of the bonding pads 21 are etched by
the non-anisotropic etching. Here, since the side surfaces of the
bonding pads 21 are formed by the wet etching, they have a curved
structure and thus the anchor effect is generated by such curved
structure. In this case, if Al is employed as material, the
anisotropic etching may be applied and thus the finer pattern than
the case where cu is employed can be formed. In either case, it is
preferable that the etching method should be selected from many
etching methods to generate the anchor effect on the side
surfaces.
The present structure consists of the semiconductor element 16, a
plurality of conductive patterns 21, 15, the bonding wires 26, the
adhering means 28 between the semiconductor element and the island
15, and the insulating resin 25 for burying them.
As the adhering means 28, the brazing solder such as solder, the
conductive past, the adhesive agent formed of conductive material
or insulating material, the adhesive insulating sheet are
preferable.
As the insulating resin 25, thermosetting resin such as epoxy
resin, thermoplastic resin such as polyimide resin, polyphenylene
sulfide, etc. can be employed.
Also, if the resin is formed by the mould or the resin may be
coated by dipping or coating, any resin may be employed as the
insulating resin. Also, as the conductive patterns constituting the
bonding pads 21 and the island 15, the conductive leaf containing
Cu as major material, the conductive leaf containing Al as major
material, the Fe--Ni alloy, the Al--Cu laminated body, the
Al--Cu--Al laminated body, etc. maybe employed. Of course, other
conductive materials maybe employed. In particular, the conductive
material that can be etched and the conductive material that can
evaporated by the laser are preferable. Also, in light of the
half-etching characteristic, the formability by the plating, the
thermal stress, the flexibility, the conductivity, and the thermal
conductivity, the conductive material containing the rolling-formed
Cu as the major material is preferable.
The present invention has such a feature that, since the insulating
resin 25 and the adhering means 28 are also filled in a separating
groove 30, omission of the conductive pattern can be prevented.
Also, the side surfaces of the bonding pads 21 are formed as the
curved structure by applying the non-unisotropic etching by
employing the dry etching or the wet etching as the etching to
generate the anchor effect. As a result, the structure can be
achieved in which the conductive patterns 15, 21 do not come out
from the insulating resin 25.
In addition, the back surface of the island 15 is exposed from the
back surface of the package. Accordingly, the back surface of the
island 15 can be brought into contact with or be adhered to the
metal plate 23 shown in FIG. 7A, the second supporting member
(radiation substrate) 13A shown in FIG. 1, or can be brought into
contact with or be adhered to the first metal film 14 coated on the
second supporting member 13A. According to this structure, the heat
generated from the semiconductor element 16 can be radiated and
thus the increase in temperature of the semiconductor element 16
can be prevented. As a result, the driving current and the driving
frequency of the semiconductor element 16 can be increased. The
reason for using the expression of "contact" is that the adhering
means such as the solder, etc. can come into contact with the Al
substrate on the surface of which only the oxide film is
formed.
Also, in the semiconductor device 10A, since the bonding pads 21
and the island 15 are supported by the insulating resin 25 as the
sealing resin, the supporting substrate is omitted. This
configuration is a feature of the present invention. Since the
conduction paths of the semiconductor device in the prior art are
supported by the supporting substrate (the flexible sheet, the
printed circuit board, or the ceramic substrate) or the lead frame,
the configurations that may be essentially omitted are added.
However, since the present circuit device is constructed by the
necessary and lowest minimum constituent elements so as to omit the
supporting substrate, the reduction in size and weight can be
achieved and also a material cost can be suppressed. Therefore, the
semiconductor device 10A becomes inexpensive in cost.
Also, the bonding pad 21 and the island 15 are exposed from the
back surface of the package. If the brazing solder such as solder,
etc. is coated on this area, the island 15 gets wet in the brazing
solder with a different thickness because the island 15 has a wide
area. Therefore, in order to make the film thickness of the brazing
solder uniform, an insulating film 31 is formed on the back surface
of the semiconductor device 10A. A rectangular dotted line 32 in
FIG. 6A indicates an exposed area exposed from the insulating film
31. Here, since the back surfaces of the bonding pads 21 are
exposed as a rectangular shape, the same sizes as those shapes are
exposed from the insulating film 31. In this case, it is needless
to say that various shapes such as the circle, the ellipse, etc.
maybe selected as the shape.
Accordingly, since the areas wetted by the brazing solder have
substantially the same size, the thickness of the brazing solder
formed here becomes substantially equal. This is true after the
solder print or the solder reflow. It is possible to say that this
is true of the conductive paste such as Ag, Au, Ag--Pd, etc.
According to this structure, it can be calculated with good
precision how much the back surface of the metal plate 23 described
later is projected from the back surface of the bonding pads 21.
Also, as shown in FIG. 6B, if the solder balls 22 are formed, the
failure in soldering can be eliminated since bottom ends of all
solder balls come into contact with the conduction paths of the
flexible sheet.
Also, the exposed areas 32 of the island 15 maybe formed larger
than the exposed size of the bonding pads 21 by taking account of
the heat radiation of the semiconductor element, otherwise the
entire area of the island 15 may be exposed from the insulating
film 31. In this case, it is possible to omit the coating of the
insulating film 31.
Also, the conductive pattern 33 provided on the first supporting
member (flexible sheet) 11 can be extended to the back surface of
the semiconductor device 10A as it is by providing the insulating
film 31. In general, the conductive pattern 33 provided on the
first supporting member (flexible sheet) 11 side is arranged to
detour the adhering area of the semiconductor device, but such
conductive pattern 33 can be arranged without the detour because of
formation of the insulating film 31. In addition, since the
insulating resin 25 is projected from the conductive pattern, the
clearance can be formed between the wirings 33 on the first
supporting member (flexible sheet) 11 and the conductive pattern
21, 15. Thus, merits such as prevention of the short-circuit,
facilitation of the cleaning, etc. can be achieved.
[Fourth Embodiment Explaining the Semiconductor Device]
The semiconductor device 10B shown in FIG. 7A corresponds the
semiconductor device 10A shown in FIG. 6 to which the metal plate
23 is adhered. Accordingly, since elements other than the metal
plate 23 are substantially similar to FIG. 6, different elements
will be explained.
A reference 28 is the adhering means, and is projected from the
bonding pads 21 and the island 15, as can be seen from the
manufacturing method described later. Then, an amount of projection
of the back surface of the metal plate 23 can be simply adjusted by
a thickness of the metal plate 23. For example, if the metal plate
23 is pushed against the adhering means 28 when the brazing solder
22 is melted, the thickness of the solder between the metal plate
23 and the island 15 can be decided based on an amount of
projection of the adhering means 28.
Therefore, if the thickness of the metal plate 23 is decided, it
can be calculated how long the back surface of the metal plate 23
is projected from the back surface of the external connection
electrode 29A (or the lowermost end of the solder balls 40).
Accordingly, as shown in FIG. 1A, if the surface of the radiation
substrate 13A is positioned lower than the mounting surface of the
first supporting member (flexible sheet) 11, the back surface of
the metal plate 23 can be brought into contact with the radiation
substrate 13A by forming the radiation substrate 13A after the
amount of projection is calculated precisely.
[Fifth Embodiment Explaining the Semiconductor Device]
Then, FIG. 7B will be explained hereunder. In this semiconductor
device 10C, the island 15 and the metal plate 23 are formed
integrally. This manufacturing method will be explained later with
reference to FIG. 21 to FIG. 23.
Since the island 15 and the metal plate 23 can be worked from the
same conductive leaf by etching, there is no necessity to stick the
metal plate 23, unlike FIG. 7A. If an amount of etching is
controlled, it can be controlled with good precision how long the
back surface of the metal plate 23 is projected from the back
surface of the bonding pads 21 (or the lowermost end of the solder
balls 40). Accordingly, like FIG. 7A, if the surface of the
radiation substrate 13A is formed lower than the mounting surface
of the first supporting member (flexible sheet) 11, the back
surface of the metal plate 23 can be brought into contact with the
radiation substrate 13A by forming the radiation substrate 13A
after the amount of projection is calculated precisely.
[Sixth Embodiment Explaining the Semiconductor Device]
In the semiconductor device 10D shown in FIG. 8A, the island 15
shown in FIG. 6, FIG. 7 is omitted. If the area acting as the
island 15 is also omitted in steps in FIG. 17, the back surface of
the semiconductor element 16 is exposed from the insulating resin
25, and thus the back surface of the semiconductor element 16 and
the back surfaces of the bonding pads 21 are substantially at the
same surface level.
In this case, the surface of the semiconductor element 16 can be
positioned lower than the surface of the semiconductor element 16
shown in FIG. 6, FIG. 7. Therefore, this semiconductor device has
such a feature that, since the uppermost portions of the bonding
wires 26 can be positioned on the lower side, the thickness of the
insulating resin 25 can be reduced correspondingly and thus the
overall size can be formed thin.
Since this semiconductor device is similar to that in FIG. 6 except
this feature, following explanation will be omitted.
[Seventh Embodiment Explaining the Semiconductor Device]
The semiconductor device 10E in FIG. 8B corresponds to the
semiconductor device in FIG. 8A to which the metal plate 23 is
attached. The reason for attaching the metal plate 23 is identical
to that in FIG. 7A, i.e., to project the back surface of the metal
plate 23 rather than the back surfaces of the bonding pads 21. If
the radiation substrate 13A with which the semiconductor device 10E
is brought into contact is arranged lower than the back surface of
the bonding pads 21 (or lower ends of the solder balls 40), the
semiconductor device 10E can contact to the radiation substrate 13A
via the metal plate 23 acting as the projection.
[Eighth Embodiment Explaining the Semiconductor Device]
The semiconductor device 10F in FIG. 8C can be formed by
half-etching an area acting as the island 15 and then adhering the
back surface of the semiconductor element 16 to the separating
groove in the manufacturing method in FIG. 21, and projecting the
conductive leaf 70, that is positioned on the back surface of the
semiconductor element 16, to the back surface side in steps in FIG.
22. If the radiation substrate 13A with which the semiconductor
device 10F is brought into contact is arranged lower than the back
surface of the bonding pads 21 (or the lower ends of the solder
balls 40), the semiconductor device 10F can contact to the
radiation substrate 13A via the metal plate 23 acting as the
projection.
The semiconductor device, in which the face up type semiconductor
element explained above in FIG. 6 to FIG. 8C is built, is
electrically connected to the conductive pattern 33 on the first
supporting member (flexible sheet) 11 like FIG. 1, and
simultaneously the island of the semiconductor device is adhered to
the first metal film 14 formed on the second supporting member 13A.
Also, the metal plate 23 formed on the back surface of the
semiconductor device is adhered to the first metal film 14 formed
on the second supporting member 13A. Especially, since the first
metal film 14 consists of the film containing Cu as major material,
the film containing Au as major material, or the film containing Ag
as major material, the balls 22 made of brazing solder such as
solder, etc. can be adhered to the first metal film 14 in FIG. 6,
FIG. 8A and also the metal plate 23 can be adhered to the first
metal film 14 via the brazing solder or the conductive paste in
FIG. 7A, FIG. 7B, FIG. 8B, FIG. 8C.
In this case, if the Al substrate on the surface of which the oxide
film is formed is used as the radiation substrate, the balls may be
melted and brought into contact.
As a result, since the back surface of the semiconductor element 16
is satisfactorily thermally coupled with the radiation substrate
13A, the heat generated from the semiconductor element can be
radiated from the radiation substrate 13A to the metal member
constituting an electronic equipment. Thus, the driving ability of
the semiconductor element can be improved.
In addition, features of the present invention will be explained in
detail. The flexible sheet 11 is made of sheets which are formed of
insulating material such as polyimide, etc. to sandwich the
conductive pattern. In some cases, the multi-layered structure
maybe employed. For the convenience of explanation, the flexible
sheet having a single layer wiring will be explained herein. Pad
electrodes PD are exposed, and two opening portions are provided on
the inside of the pad electrodes PD to expose the radiation
substrate 13A.
The flexible sheet 11 in FIG. 1 mainly consists of a first
insulating sheet P1, the conductive pattern 33, and a second
insulating sheet P2. The first insulating sheet P1, to which the
conductive pattern 33 is adhered via the adhesive, functions as the
supporting substrate. The second insulating sheet P2 functions as
the protection film of the conductive pattern 33. The adhesive is
provided between the conductive pattern 33 and the second
insulating sheet P2. Then, the first opening portion OP is formed
in the second insulating sheet P2 to expose the pad electrodes PD.
The second opening portion 13 is formed in the first insulating
sheet P1 to expose the surface of the radiation substrate 13A. The
first opening portion OP must be opened wider than the second
opening portion 13 to expose the pad electrodes PD. The second
opening portion 13 has a size which can expose the island 15 or a
size which can expose the metal plate 23.
A feature of the present invention resides in that the contact area
CT, with which the back surface of the semiconductor device,
particularly the insulating resin 25 comes into contact, is formed
in the first opening portion OP and simultaneously at least one
side L is arranged on the outer side than the arranging area of the
semiconductor device 10.
An enlarged view of this portion is shown in FIG. 2. FIG. 2A is a
plan view, FIG. 2B is a sectional view taken along an A-A line, and
FIG. 2C is a sectional view taken along an B-B line.
This structure makes it possible to increase the adhering strength
by assuring the thickness of the solder balls 22 of the
semiconductor device 10 and also clean the back surface of the
semiconductor device 10.
First, in order to hold the thickness of about 40 to 60 .mu.m by
the second insulating sheet P2 and the adhesive AH in total,
inventors of the present invention brings the back surface of the
insulating resin 25 into contact with the first insulating sheet P1
to assure the thickness of the solder 22. However, since the entire
periphery of the back surface of the semiconductor device 10 comes
into contact with the first insulating sheet P1, it is impossible
to execute the cleaning of the back surface of the semiconductor
device 10.
Therefore, as shown in FIG. 2A and FIG. 2C, if the first opening
portion OP other than the contact area CT is positioned on the
outer side than the arranging area of the semiconductor device 10,
the cleaning liquid can enter from a portion indicated by an arrow.
This structure is suitable for the filling of underfill material to
prevent the degradation and the disconnection of the solder.
For example, the impurity such as the flux, etc. is generated in
the clearance between the semiconductor device 10 and the flexible
sheet after the back surface electrodes PE and the pad electrodes
PD are connected via the solder balls 22. At this time, the
clearance can be cleaned via the opening portion indicated by the
arrow. In addition, since the underfill material can be injected,
the adhering strength of the solder 22 and the reliability can be
improved.
FIG. 3 shows a variation of the contact area CT. In FIG. 2, the
contact area CT that has a quadrant at a corner portion of the
first opening portion OP respectively is formed. In FIG. 3, the
projection portion CT which enables to contact to the back surface
of the insulating resin 25 from four sides of the first opening
portion OP is provided.
FIG. 4 shows another variation of the contact area CT. Here,
spacers SP are arranged as the contacting means on the back surface
of the semiconductor device 10. Such spacers can be formed by
various methods.
First of all, as shown in FIG. 4A, the spacers are adhered to the
flexible sheet or the back surface of the semiconductor device.
Here, the first insulating sheet P1 is left like the island to form
the spacers SP. FIG. 4C and FIG. 4D show spacers which are formed
simultaneously when the back surface electrodes PE are formed. If
the electrodes are formed to project rather than the back surface
electrodes PE, they can function as the spacer. In FIG. 4C, the
spacers come into contact with the pad electrodes PD formed on the
flexible sheet. In FIG. 4D, the spacers come into contact with the
bottom surface of the opening portion, i.e., the first insulating
sheet P1 or the insulating adhesive provided on the first
insulating sheet P1.
At least three contact areas CT or the spacers SP should be formed.
This is true of all semiconductor modules.
Then, the semiconductor module that is slightly different from the
semiconductor module shown in FIG. 1 is shown in FIG. 9. This
module employs the face down semiconductor element 16 as shown in
FIG. 10 to FIG. 12. In this case, since the module is almost
similar except using the face down semiconductor element 16, only
simple explanation will be given. Also, since the radiation
substrate employed as the second supporting member 13A is identical
to that in the second embodiment, its explanation will be
omitted.
In FIG. 9, the semiconductor element 16 is mounted in a face-down
fashion, and the back surface electrodes PE and the bonding
electrodes 27 of the semiconductor element 16 are connected
together via the brazing solder such as solder, etc. or bump
electrodes. Therefore, the thickness of the package can be reduced
thinner than the structure employing the bonding wires 26 in FIG.
6. But the back surface of the semiconductor element 16 is
thermally coupled with the island 15 in FIG. 6 whereas the
semiconductor element 16 described herein is inferior in thermal
resistance since such semiconductor element 16 is adhered by the
insulating adhering means 50. However, this thermal resistance can
be reduced by mixing fillers into the insulating adhering means 50.
In addition, there is such a merit that impedances of the bonding
electrodes 27 and the back surface electrodes 21 can be set lower
than that of the face-up semiconductor element because of the
shorter path.
[Ninth Embodiment Explaining the Semiconductor Device]
First, the semiconductor device of the present invention will be
explained with reference to FIG. 10. FIG. 10A is a plan view of the
semiconductor device, and FIG. 10B is a sectional view taken along
an A-A line.
In FIG. 10, following constituent elements are buried in the
insulating resin 25. That is, the back surface electrodes 21, the
radiation electrode 15A provided in the area surrounded by the back
surface electrodes 21, and the semiconductor element 16 provided on
the radiation electrode 15A are buried. In this case, the radiation
electrode 15A corresponds to the island 15 in FIG. 6. However,
since the semiconductor element 16 is mounted in a face-down
fashion, it can be adhered to the radiation electrode 15A via the
insulating adhering means 50. The radiation electrode 15A is
divided into four areas in view of the adhesiveness. A separating
groove formed by this four division is indicated by a reference 29.
A reference 30 denotes a separating groove formed between the back
surface electrodes 21 and the radiation electrodes 15A. Also, the
radiation electrode 15A are not divided into plural pieces and, as
shown in FIG. 6, may be formed as a single electrode.
Also, if the clearance between the semiconductor element 16 and the
radiation electrodes 15A is narrow and thus the insulating adhering
means 50 is hard to enter into the clearance, grooves, as indicated
by 51, that are shallower in depth than the separating grooves 29,
30 may be formed on the surface of the radiation electrode 15A.
Also, the bonding electrodes 27 of the semiconductor element 16 and
the back surface electrodes 21 are electrically connected to each
other via the brazing solder such as solder, etc. Stud bumps such
as Au, etc. may be employed in place of the solder. For example,
the bumps are provided to the bonding electrodes 27 of the
semiconductor element 16 and then the bumps may be connected by the
ultrasonic wave or the welding with pressure. Also, reduction in
the connection resistance and improvement of the adhering strength
may be achieved by providing the solder, the conductive paste, or
the anisotropic conductive particles in the peripheries of the
pressure-welded bumps.
Also, the back surfaces of the pads 21 are exposed from the
insulating resin 25 and acts as the external connection electrode
29A as it is. The side surfaces of the back surface electrodes 21
are etched by the non-unisotropic etching. Here, the side surfaces
have a curved structure since they are formed by the wet etching,
the anchor effect is generated by the curved structure.
Also, in the arranging area of the semiconductor element 16, the
insulating adhering means 50 is formed on the radiation electrode
15A, on the back surface electrodes 21 and between them.
Especially, the insulating adhering means 50 is provided in the
separating grooves 29 formed by the etching and the back surface of
the insulating adhering means is exposed from the back surface of
the semiconductor device 10G. Also, all the elements including them
are sealed by the insulating resin 25. Then, the back surface
electrodes 21 . . . , the radiation electrode 15A, and the
semiconductor element 16 are supported by the insulating resin 25
and the insulating adhering means 50.
The adhesive formed of insulating material, or underfill material
having high osmosis are preferable as the insulating adhering means
50. In the case of the adhesive, such adhesive is coated previously
on the surface of the semiconductor element 16 and then
semiconductor element 16 is adhered by the pressure welding when
the back surface electrodes 21 are connected by using the Au bumps
instead of the solder 52. In the case of the underfill material,
such underfill material may penetrate into the clearance after the
solder 52 (or the bumps) and the back surface electrodes 21 are
connected to each other.
Since the insulating resin and the conductive pattern are similar
to the above embodiments, their explanation will be omitted.
In the present invention, like the above embodiment, since the
insulating resin 25 and the insulating adhering means 50 are filled
in the separating grooves 29, the coming-off of the conductive
pattern can be prevented. Also, the side surfaces of the conductive
patterns can be formed as the curved structure to generate the
anchor effect. As a result, the structure in which the back surface
electrodes 21 and the radiation electrode 15A are not come out from
the insulating resin 25 can be implemented.
Also, the back surface of the radiation electrode 15A is exposed
from the back surface of the package. Hence, the back surface of
the radiation electrode 15A can be adhered to the second supporting
member 13A or the first metal film 14 on the second supporting
member 13A via the solder or the conductive paste. According to
this structure, the heat generated from the semiconductor element
16 can be radiated and thus the increase in temperature of the
semiconductor element 16 can be prevented. As a result, the driving
current and the driving frequency of the semiconductor element 16
can be increased correspondingly.
Like the above embodiment, the semiconductor device 10G of the
present invention does not need the supporting substrate, the
reduction in size and weight can be achieved. Thus, the
semiconductor device can be packed in the arm or the suspension of
the hard disk.
Also, since the exposed areas 32 exposed from the insulating film
31 are set substantially equal in level to the back surfaces of the
back surface electrodes 21, the thickness of the formed brazing
solder become substantially equal.
[Tenth Embodiment Explaining the Semiconductor Device 10H]
A sectional view of the semiconductor device 10H is shown in FIG.
11A. A cutting direction corresponds to an A-A line in FIG. 10. In
this case, the semiconductor device 10H is constructed by attaching
the metal plate 23 to the structure in FIG. 10. Now, different
portions will be explained herein.
A reference 50 is the insulating adhering means. As can be seen
from the manufacturing method described later, the insulating
adhering means is projected from the back surface electrodes 21 and
the radiation electrode 15A. Accordingly, if an amount of
projection of the metal plate 23 must be controlled with high
precision, the thickness of the solder between the radiation
electrode 15A and the metal plate 23 can be maintained constant by
pushing the metal plate 23 against the convex portion of the
insulating adhering means 50 when the brazing solder 22 is
melted.
Accordingly, if the thickness of the metal plate 23 is decided, it
can be calculated how long the back surface of the metal plate 23
is projected from the back surface of the back surface electrodes
21 (or the lowermost ends of the solder balls 40).
Therefore, as shown in FIG. 9, if the surface of the radiation
substrate 13A is formed lower than the mounting surface of the
first supporting member 11, the back surface of the metal plate 23
can be brought into contact with or be adhered to the radiation
substrate 13A by forming the radiation substrate 13A after the
amount of the projection is calculated precisely.
[Eleventh Embodiment Explaining the Semiconductor Device 10I]
Then, FIG. 11B will be explained. In the semiconductor device 10I,
the radiation electrode 15A and the metal plate 23 are formed
integrally. In this case, the manufacturing method will be
described later in FIG. 21 to FIG. 23.
The radiation electrode 15A and the metal plate 23 are worked from
the same conductive leaf by etching. Hence, contrary to FIG. 11A,
it is possible to eliminate the necessity to stick the metal plate
23. If an amount of etching is controlled, it can be controlled
with good precision how long the back surface of the metal plate 23
is projected from the back surface of the back surface electrodes
21 (or the lower ends of the solder balls 40). Accordingly, like
FIG. 7B, if the surface of the radiation substrate 13A is formed
lower than the mounting surface of the first supporting member 11,
the back surface of the metal plate 23 can be brought into contact
with or be adhered to the radiation substrate 13A by forming the
radiation substrate 13A after the amount of projection is
calculated precisely.
Then, three semiconductor devices shown in FIG. 12 will be slightly
explained hereunder. Three semiconductor devices 10J to 10L have a
structure substantially identical to the semiconductor devices
shown in FIG. 10 and FIG. 11. A difference is that the surface of
the radiation electrode 15A is arranged higher than the surfaces of
the back surface electrodes 21. Accordingly, a predetermined
interval is provided between the bonding electrodes 27 and the back
surface electrodes 21.
[Twelfth Embodiment Explaining the Semiconductor Device 10J]
The semiconductor device 10J shown in FIG. 12A is substantially
identical to FIG. 10. A difference is that the surface of the
radiation electrode 15A is arranged higher than the surfaces of the
back surface electrodes 21. Here, this difference will be
explained.
The present invention has such a feature that the surface of the
radiation electrode 15A is projected in contrast to the surfaces of
the back surface electrodes 21.
As the means for connecting the back surface electrode 21 and the
bonding electrode 27, there may be considered the Au bump, the
solder ball, etc. At least one stage of Au mass is formed as the Au
bump, and the thickness of one stage is about 40 .mu.m and
thickness of two stages is about 70 to 80 .mu.m. In general, as
shown in FIG. 10B, since the surface of the radiation electrode 15A
and the surfaces of the back surface electrodes 21 coincide in
height with each other, the clearance d between the semiconductor
element 16 and the radiation electrode 15A can be substantially
decided by the thickness of the bump. Accordingly, in the case of
FIG. 10B, the clearance d cannot be reduced further more, so that
the thermal resistance generated by the clearance cannot be
reduced. However, as shown in FIG. 12A, if the surface of the
radiation electrode 15A is projected rather than the surfaces of
the back surface electrodes 21 to an extent of almost the thickness
of the bump, this clearance d can be reduced extremely. Thus, the
thermal resistance of the semiconductor element 16 and the
radiation electrode 15A can be lowered.
Also, the thickness of the solder bump or the solder ball is about
50 to 70 .mu.m. The clearance d can be reduced in the same way. In
addition, since the brazing solder such as the solder has good
wettability for the back surface electrodes 21, such brazing solder
can spread over the entire area of the back surface electrodes 21
when it is melted, and thus the thickness become thin. However,
since the clearance d between the bonding electrode 27 and the back
surface electrodes 21 is decided by the amount of projection of the
radiation electrode 15A, the thickness of the brazing solder can be
decided by this amount of projection and thus above flow of the
solder can be prevented. Accordingly, the stress applied to the
solder can be scattered because the thickness of the brazing solder
can be formed thick, and thus the degradation due to heat cycle can
be suppressed. Also, the cleaning liquid can enter into this
clearance by adjusting this amount of projection.
In FIG. 10, in order to prevent the flow of the solder, the flow
preventing film DM is formed to control the thickness of the
solder. In contrast, in FIG. 12, since the flow of the solder can
be prevented, such film DM is omitted. However, the flow preventing
film DM may be provided.
The projected structure of the radiation electrode 15A is also
applied to the semiconductor devices 10K, 10L described in the
following.
[Thirteenth Embodiment Explaining the Semiconductor Device 1OK]
The semiconductor device 10K shown in FIG. 12B is the semiconductor
device 10J shown in FIG. 12A to which the metal plate 23 is
attached. The totally same concept as that in FIG. 7A, FIG. 11A is
applied, wherein the back surface of the metal plate 23 is
projected lower than the back surface of the external connection
electrode 30 (or the lower ends of the solder balls 40).
Accordingly, the back surface of the metal plate 23 can be brought
into contact with the radiation substrate 13A shown in FIG. 9. The
details are given in the explanation in FIG. 7A, FIG. 11A.
[Fourteenth Embodiment Explaining the Semiconductor Device 10L]
In the semiconductor device 10L shown in FIG. 12C, the radiation
electrode 15A provide to the semiconductor device 10K shown in FIG.
12B and the metal plate 23 are integrally constructed. The totally
same concept as that in FIG. 7B, FIG. 11B is applied, wherein the
back surface of the metal plate 23 is projected lower than the back
surface of the external connection electrode 30 (or the lower ends
of the solder balls 40). Accordingly, the back surface of the metal
plate 23 can be brought into contact with the radiation substrate
13 shown in FIG. 9. The details are given in the explanation in
FIG. 7B, FIG. 11B.
[Fifteenth Embodiment Explaining the Semiconductor Module]
Then, the semiconductor module employing the lead frame will be
explained by using FIG. 13. Since elements other than the
semiconductor device 10 are similar to FIG. 1 and FIG. 9, only
differences will be explained herein.
The semiconductor device employed herein are the semiconductor
devices 10M, 10N shown in FIG. 14, FIG. 15.
Leads 61 are arranged around the island 60, then the island 60 and
the leads 61 are constructed by lead frames that are supported by
the supporting leads called tab lifting lead, or tie bar, then the
semiconductor element 16 is mounted, then the wire bonding is
applied, then the resultant structure is sealed by the transfer
molding, and then the supporting leads are cut off, whereby the
semiconductor device can be completed. In this case, there are the
semiconductor devices in which the leads 61 are cut.
In the semiconductor device 10M shown in FIG. 14, the back surface
of the island 60 and the back surface of the lead 61 are arranged
substantially on the same surface level, and at least the back
surface of the island 60 is exposed from the back surface of the
package. Then, the pad electrodes PD on the flexible sheet 11 and
the leads 61 are connected, and the back surface of the island 60
and the radiation substrate 13A or the back surface of the island
60 and the first metal film 14 on the radiation substrate 13A are
adhered via the second opening portion 13. As the adhering
material, the brazing solder such as the solder, etc., the
conductive paste, etc. are preferable.
The island of the semiconductor device 10 may be brought directly
into contact with the radiation substrate 13A on which the first
metal film 14 is not formed.
In contrast, in the semiconductor device 10N shown in FIG. 15, the
metal plate 23 is adhered to the island 60 and the back surface of
the metal plate 23 is projected rather than the back surfaces of
the leads 61. Accordingly, if the first metal film 14 is arranged
lower than the conductive pattern 33 forming surface, the back
surface of the metal plate 23 is projected by the length
corresponding to such low arrangement, and the adhesion of the
metal plate 23 and the first metal film 14 can be facilitated.
The island of the semiconductor device 10 maybe brought directly
into contact with the radiation substrate 13A on which the first
metal film 14 is not formed. Also, the island 60 and the metal
plate 23 may be formed integrally.
[Sixteenth Embodiment Explaining the Method of Manufacturing
Semiconductor Device]
The present manufacturing methods are almost identical although
slightly different steps are employed depending upon that the
semiconductor element is set face-up or face-down.
Here, the manufacturing method will be explained by using the
semiconductor device 10A in FIG. 6.
First, the conductive leaf 70 is prepared like FIG. 16. It is
preferable that the thickness should be set to about 10 to 300
.mu.m, and the rolled copper leaf of 70 .mu.m thickness is employed
here. Then, the conductive film 71 or the photoresist is formed on
the surface of the conductive leaf 70 as the etching resistance
mask. This pattern is the same pattern as the bonding pad 21 . . .
, and the island 15 in FIG. 6A. If the photoresist is employed in
place of the conductive film 71, a conductive film such as Au, Ag,
Pd, Ni, or the like is formed in at least the areas corresponding
to the bonding pads as the underlying layer of the photoresist.
This is provided to enable the bonding (see FIG. 16).
Then, the conductive leaf 70 is half-etched via the conductive film
71 or the photoresist. The etching depth may be set shallower than
the thickness of the conductive leaf 70. The finer pattern can be
formed as the depth of the etching is shallower and shallower.
Then, the bonding pads 21 and the island 15 appears on the
conductive leaf 70 like the convex shape by the half etching. As
described above, the Cu leaf containing the Cu formed by rolling as
the major material is employed as the conductive leaf 70. However,
the conductive leaf made of Al, the conductive leaf made of Fe--Ni
alloy, the Cu--Al laminated body, the Al--Cu--Al laminated body may
be employed. Particularly, the Al--Cu--Al laminated body can
prevent the bowing generated due to the difference in the thermal
expansion coefficient.
If the radiation electrode should be projected upward as shown in
FIG. 12, first the area corresponding to the radiation electrode is
made by half-etching, then the radiation electrode is covered with
the photoresist, and then the area corresponding to the bonding
electrode is made by half-etching once again (see FIG. 17).
Then, the conductive adhering means 28 or the insulating adhering
means is provided to the area corresponding to the island 15, then
the semiconductor element 16 is adhered, and then the bonding
electrodes 27 of the semiconductor element 16 and the bonding pads
21 are electrically connected mutually. The semiconductor element
16 is mounted in a face-up fashion, the bonding wires 26 are
employed as the connecting means. Also, in the case of the face
down, the solder balls or the bumps are employed (see FIG. 18).
Then, the insulating resin 25 is formed to cover the bonding pads
21 formed by the half-etching, the semiconductor element 16, and
the metal wires 26. Any of the thermoplastic resin and the
thermosetting resin may be employed as the insulating resin.
In the present embodiment, the thickness of the insulating resin is
adjusted to cover a height of about 100 .mu.m upward from the top
portion of the metal wires 26. This thickness can be increased or
decreased in light of the strength of the semiconductor device.
In the resin injection, since the bonding pads 21, the island 15
are formed integrally with the sheet-like conductive leaf 70,
positional displacement of the conductive leaf patterns are never
generated unless the displacement of the conductive leaf 70 is
caused. In addition, no resin flash is produced.
As described above, the bonding pads 21 and island 15 formed as the
convex portions, and the semiconductor element 16 are buried into
the insulating resin 25, and the conductive leaf 70 located lower
than the convex portions is exposed from the back surface (see FIG.
19).
Then, the conductive leaf 70 exposed from the back surface of the
insulating resin 25 is removed, and the bonding pads 21 and the
island 15 are separated individually.
Various methods may be considered as this separating step. They may
be separated by removing the back surface by the etching, or they
may be separated by scraping by virtue of polishing or grinding.
Also, both methods maybe employed.
Also, if a plurality of units each consisting of the semiconductor
device 10A are formed integrally, the dicing step is added after
this separating step.
They are separated individually by employing the dicing apparatus,
but the chocolate brake, the press, or the cutting may be
employed.
Here, after the Cu pattern is separated, the insulating film 31 is
formed on the bonding pads 21 and the island 15 separated and
exposed on the back surface, and then the insulating film 31 is
patterned to expose the areas indicated by a dotted line in FIG.
6A. After this, the module is subjected to the dicing along the
lines indicated by an arrow to cut out the semiconductor device
10A.
The solder 22 may be formed before or after the dicing.
According to the above manufacturing method, the small and
lightweight package in which the bonding pads and the island a
reburied in the insulating resin can be accomplished.
Then, the method of manufacturing the semiconductor device in which
the metal plate 23 and the island 15 are formed integrally will be
explained with reference to FIG. 21 to FIG. 23 hereunder. Since the
similar steps maybe employed up to FIG. 19, the explanation made to
there will be omitted.
FIG. 19 shows the state in which the insulating resin 25 is coated
on the conductive leaf 70, wherein the photoresist PR is covered on
the area corresponding to the island 15. If the conductive leaf 70
is etched via the photoresist PR, the island 15 can be projected
from the back surfaces of the bonding pads 21, as shown in FIG. 22.
The conductive film such as Ag, Au, etc. is selectively formed in
place of the photoresist PR, and then may be used as a mask. This
film can also act as the oxidation preventing film.
Then, as shown in FIG. 23, after the bonding pads 21 and the island
15 are perfectly separated, the insulating film 31 is coated, and
then the areas at which the brazing solder 22 is arranged are
exposed. Then, the brazing solder 22 is adhered and then the module
is separated by the dicing at the portion indicated by an
arrow.
The semiconductor device separated in this manner is mounted on the
first supporting member 11, as shown in FIG. 1. As described above,
since the island 15 is projected, it can be jointed simply to the
first metal film 14 via the solder, etc.
In the semiconductor device explained in above all embodiments, the
size of the island 15 (or the radiation electrode) may be reduced,
the wirings formed integrally with the bonding pads 21 (or pads)
may be extended to the back surface of the semiconductor element
16, and new external connecting electrodes may be provided there.
This pattern is provided based on the same concept as the rewiring
used in BGA, etc. There is such a merit that the stress in
respective connecting portions can be relaxed by the rewiring.
Also, since the wirings and the external connecting electrodes are
provided on the back surface of the semiconductor element, the
insulating adhering means 50 must be formed of insulating material.
Also, the back surface of the rewiring is covered with the
insulating film 31.
[Seventeenth Embodiment Explaining the Semiconductor Module]
As described above, in all modules, the second opening portion 13
is formed to expose the radiation substrate. However, the present
invention may be applied to the module in which the second opening
portion 13 is not formed at the sacrifice of the radiation
characteristic, as shown in FIG. 24. The land is formed on the
first insulating sheet P1, and then the island 15 or the metal
plate of the semiconductor device 10 may be brought into contact
with or adhered to this land. All semiconductor devices described
above may be employed as this semiconductor device. Also, the
radiation substrate 13 may be stuck to the back surface or may be
omitted.
As apparent from the above explanation, the radiation substrate of
the present invention has excellent heat radiating characteristic
by forming the first metal film containing Cu, Ag, or Au as the
major material on the radiation substrate containing Al as the
major component.
Since the growth of the oxide film is small on the radiation
substrate containing Al as the major material, the generation of
particles is small correspondingly, and also the malfunction of the
electronic equipment mounted in the inside can be reduced. In
addition, the first metal film containing Cu, Ag, or Au as the
major material can be formed on the surface of Al, and also the
metal body (e.g., the island or the radiation electrode) exposed
from the back surface of the semiconductor device can be thermally
coupled with the first metal film via the conductive adhering
material. Accordingly, such radiation substrate can serve as the
radiation substrate that generates a small amount of particles and
has excellent thermal conduction.
Also, the first metal film can be formed by the plating, and the
radiation substrate having small thermal resistance can be
implemented.
Also, since the semiconductor device in which the metal plate is
adhered to the metal body exposed to the back surface of the
package and the metal plate is projected rather than the back
surfaces of the external connecting electrodes or the pads can be
provided, there is such a merit that mounting into the FCA can be
facilitated.
Also, since the opening portion is provided to the FCA and the back
surface of the FCA and the radiation electrode of the semiconductor
device are positioned on the same surface level, the contact to the
second supporting member can be facilitated.
Also, since Al is used as the second supporting member, and the
first metal film made of Cu is formed there, and the radiation
electrode or the metal plate can be adhered to the metal film, the
heat generated from the semiconductor element can be radiated to
the outside via the second supporting member.
In addition, since the thickness of the solder can be assured by
bringing the back surface of the semiconductor device into contact
with the contact area and a part of the first opening portion is
arranged on the outer side than the arranging area of the
semiconductor device, the clearance provided on the back surface of
the semiconductor device can be cleaned. Also, the underfill
material can be mixed, and the reliability of connected portions of
the solder balls can be improved.
Therefore, the temperature increase of the semiconductor element
can be prevented, and thus the performance close to the natural
ability can be extracted. In particular, since the FCA mounted in
the hard disk can emit the heat to the outside effectively, the
reading/writing speed of the hard disk can be increased.
* * * * *